Led driving device and lighting apparatus

Abstract

A light emitting diode (LED) driving device includes a driving circuit configured to output a driving current for driving a plurality of LEDs using an input voltage, a protection circuit configured to generate a sensing voltage by detecting the input voltage, and a control circuit configured to control the driving circuit by detecting the sensing voltage and the driving current. The protection circuit includes a circuit element having hysteresis characteristics in response to the input voltage that is increased to be greater than a predetermined reference voltage or is decreased to be less than the predetermined reference voltage.

What is claimed is: 
     
         1 . A light emitting diode (LED) driving device, comprising:
 a driving circuit configured to output a driving current for driving a plurality of LEDs using an input voltage;   a protection circuit configured to generate a sensing voltage by detecting the input voltage, and comprising a circuit element having hysteresis characteristics in response to the input voltage that is increased to be greater than a predetermined reference voltage or is decreased to be less than the predetermined reference voltage; and   a control circuit configured to control the driving circuit by detecting the sensing voltage and the driving current.   
     
     
         2 . The LED driving device of  claim 1 , wherein the protection circuit is configured to turn on the circuit element to decrease the sensing voltage in response to the input voltage that is increased to be greater than the predetermined reference voltage. 
     
     
         3 . The LED driving device of  claim 2 , wherein the control circuit is configured to control the driving circuit to output the driving current in response to the sensing voltage that is decreased to be less than a predetermined threshold voltage. 
     
     
         4 . The LED driving device of  claim 2 , wherein the protection circuit is configured to decrease the sensing voltage to be less than a predetermined threshold voltage after a predetermined time delay in response to the circuit element that is turned on. 
     
     
         5 . The LED driving device of  claim 4 , wherein the control circuit is configured to control the driving circuit to output the driving current in response to the sensing voltage that is decreased to be less than the predetermined threshold voltage. 
     
     
         6 . The LED driving device of  claim 1 , wherein the driving circuit comprises at least one of a boost converter and a buck converter configured to generate a constant current for driving the plurality of LEDs, and
 wherein the control circuit is configured to control an operation of a switching element included in at least one of the boost converter and the buck converter.   
     
     
         7 . The LED driving device of  claim 6 , wherein the control circuit is configured to control the operation of the switching element by using the sensing voltage as an analog dimming signal. 
     
     
         8 . The LED driving device of  claim 1 , wherein in response to the input voltage that is decreased, the protection circuit is configured to decrease the sensing voltage such that a decreased level of the sensing voltage is greater than a decreased level of the input voltage. 
     
     
         9 . The LED driving device of  claim 8 , wherein in response to the input voltage that is decreased, the control circuit is configured to control the driving circuit to decrease the driving current according to the decreased level of the sensing voltage. 
     
     
         10 . The LED driving device of  claim 1 , wherein the driving circuit further comprises a current detection circuit comprising a detection resistor configured to detect the driving current and a switching element configured to cut off the driving current applied to the plurality of LEDs. 
     
     
         11 . The LED driving device of  claim 1 , further comprising a power supply configured to generate the input voltage and configured to provide a direct current (DC) voltage to the driving circuit and the protection circuit. 
     
     
         12 . The LED driving device of  claim 1 , wherein the sensing voltage is input to one of an input terminal of a comparator included in the control circuit, an input terminal of a dimming circuit included in the control circuit, or an input pin of the control circuit provided as an integrated circuit. 
     
     
         13 . The LED driving device of  claim 1 , wherein the protection circuit comprises:
 a field effect transistor (FET) provided as the circuit element;   a voltage dividing resistor configured to divide the input voltage and transfer the divided input voltage to the FET; and   a hysteresis resistor connected between a drain terminal and a source terminal of the FET and having hysteresis characteristics.   
     
     
         14 . A light emitting diode (LED) driving device, comprising:
 a driving circuit comprising a first switch configured to drive a plurality of LEDs using a driving current;   a protection circuit comprising a second switch configured to be turned on and off according to an input voltage with respect to a predetermined reference voltage and output a sensing voltage; and   a control circuit configured to control the first switch of the driving circuit based on the sensing voltage and the driving current.   
     
     
         15 . The LED driving device of  claim 14 , wherein the second switch is configured to be turned on to decrease the sensing voltage in response to the input voltage that is increased to be greater than the predetermined reference voltage, and
 wherein the control circuit is configured to turn off the first switch to output the driving current in response to the sensing voltage that is decreased to be less than a predetermined threshold voltage.   
     
     
         16 . The LED driving device of  claim 14 , wherein the second switch is configured to be turned on to decrease the sensing voltage in response to the input voltage that is increased to be greater than the predetermined reference voltage,
 wherein the protection circuit is configured to decrease the sensing voltage to be less than a predetermined threshold voltage after a predetermined time delay using a time-delay circuit element in response to the second switch that is turned on, and   wherein the control circuit is configured to control the driving circuit to use the driving current in response to the sensing voltage that is decreased to be less than the predetermined threshold voltage.   
     
     
         17 . The LED driving device of  claim 14 , wherein the driving circuit further comprises:
 a detection resistor configured to detect the driving current; and   a third switch configured to cut off the driving current applied to the plurality of LEDs in response to the input voltage that is decreased to be less than the predetermined reference voltage.   
     
     
         18 . A lighting apparatus, comprising:
 a light source including a plurality of light emitting diodes (LEDs);   a power supply configured to generate an input voltage for operating the light source; and   a light emitting diode (LED) driving device including:
 a driving circuit configured to output a driving current for driving the plurality of LEDs using the input voltage, the driving circuit including a converter configured to generate the driving current; 
 a protection circuit configured to generate a sensing voltage by detecting the input voltage, the protection circuit including a circuit element having hysteresis characteristics in response to the input voltage that is increased to be greater than a predetermined reference voltage or is decreased to be less than the predetermined reference voltage; and 
 a control circuit configured to control the driving circuit by detecting the sensing voltage and the driving current. 
   
     
     
         19 . The lighting apparatus of  claim 18 , wherein the protection circuit comprises:
 a field effect transistor (FET);   a voltage dividing resistor configured to divide the input voltage and transfer the divided input voltage to the FET; and   a hysteresis resistor connected between a drain terminal and a source terminal of the FET, and having hysteresis characteristics.   
     
     
         20 . The lighting apparatus of  claim 18 , wherein the protection circuit is configured to decrease the sensing voltage to be less than a predetermined threshold voltage after a predetermined time delay, in response to the input voltage that is increased to be greater than a predetermined reference voltage.